In recent years, automobile manufacturers have directed an increasing amount of attention towards providing improved side impact protection for vehicle passengers. One of the viable methods includes providing an inflatable airbag mounted to the seat back frame of a passenger seat. Seat mounted side impact inflatable airbags (SIAB) fall into two general categories. The first type of seat mounted SIABs deploys from a visible, discrete door on the outboard side of the seat back or seat cushion bolster. The other type of seat mounted SIABs is stowed beneath the seat trim and is designed to deploy through the trim cover.
In some respects, the first type has an advantage in that the technology for the deployment of an airbag through a discrete door has been already developed for frontal airbags in steering wheels and instrument panels. The first type has the disadvantage, however, in that the location of the SIAB is generally limited to the side of the seat so that the visible door is not a part of the seating surface engaged by a seat occupant. If it is desired for the airbag to deploy through the front corner of the seat back, such as the location of a bolster seam, the first type of seat mounted SIABs cannot be used. Rather, the second type of seat mounted SIABs must be used, typically under the trim cover and the foamed padding such that the airbag does not adversely affect the seat comfort.
One of the recent developments for the second type of seat mounted side impact airbags includes the use of a cavity liner for directing the force of the airbag in a direction towards a particular seam. One of the disadvantages of a cavity liner, however, is that the cavity liner is typically topstitched into the trim cover for the seat back of the passenger seat. The front corner of the seat back is one of the most visible aspects of the passenger scat and a topstitch at the bolster seam is considered by prospective buyers of expensive automobiles as an aesthetically unpleasant feature. Thus, there is a need to provide a seat mounted side impact airbag without any visible topstitches in the bolster seam of the passenger seat.